Dave Hartnett is a tax expert. Without tax expertise the state can't collect revenue. Without revenue, public services founder. Without public services society falls apart. That syllogism needs to be borne in mind by the former permanent secretary's critics.

If Hartnett is to carry personal responsibility for failing to collect revenue owed by Vodafone and Goldman Sachs, he must also be accorded a personal role, over many years, in securing the flow of billions into the Inland Revenue and HM Revenue & Customs – a point made by Lord O'Donnell when they both appeared in front of the Commons public accounts committee last November. (And if we're in the wider blame game, O'Donnell's role in the unhappy merger of the Inland Revenue and HM Customs & Excise bears scrutiny.)

What Hartnett did, or did not do, was contained within a system of governance. That system, the PAC found, was inadequate but that does not translate into personal culpability for an official who dedicated his career to the fair and effective administration of tax law and who during it won many friends and admirers for his energy, determination and (counter cultural in Whitehall) willingness to explain and justify his actions in public hearing.

Tax officials need to spend time with recalcitrant tax payers and other sinners – and have done so since biblical times. That puts them in the firing line, in a much more direct way than other civil servants. For that they deserve credit, even if it means building around them checks, balances and scrutiny.

Tax officials need to fend off the silky attack of highly-paid QCs retained by recalcitrant tax payers. That means they need to be super able and highly adaptable – qualities Hartnett possesses in abundance. His premature exit from HMRC without the knighthood he in other circumstances would surely have deserved robbed the senior corridors of a warrior. At the Liberal Democrat conference this week Danny Alexander talks of beefing up the 'affluence unit' – but training and experience take time, and what Hartnett also brought was a career-deep expertise.

All that needs to be weighed in the balance against his judgment in the high-profile corporate cases that are the subject of the protests. Critics to the left especially need to exercise caution. Attacking senior officials can undermine the state's capacity to do what is absolutely necessary if it is to be active and generous, which is raise money – and reduce the 'tax gap'.

There's a broader point. It's coincidence that the invasion of the Hartnett dinner took place within days of the Tory chief whip Andrew Mitchell insulting the police officers guarding Downing Street – let's not quibble about his actual words.

To be effective many public servants have to be recognised as possessing legitimate authority: teachers have pedagogical skill; nurses are trained to organise their patients' care; police officers secure society by using powers to order our behaviour, and so on. Left and right can come together (in theory). Disagreeing about how big government should be, they concur that government must have authority. One side might emphasise the authority needed to levy taxes; the other might stress the need for hierarchy to be maintained.

Mitchell, a Tory, showed disrespect towards the bearers of public authority. Perhaps he has been caught up in the zeitgeisty sentiment distrustful of public institutions. Perhaps his zeal to deconstruct the state spilled over into despising its officials – his Toryism, following the lead given by Oliver Letwin and other ministers, actively wants to pull down the apparatus of government and its method is to express contempt for what government does. If that sounds like anarchy, perhaps it is.